The proposed work will serve to define and describe more clearly the pathophysiological mechanism(s) by which Clostridium perfringens type A enterotoxin causes functional and structural alterations in the intestine. This will be accomplished through studies of transport alterations induced by the enterotoxin in various cell systems, attempts to isolate an enterotoxin receptor from sensitive cell membranes, characterize in depth ultrastructural changes in the membranes of sensitive cells, and study synthesis and structure of the enterotoxin molecule.